The supplementation of a corn/barley-based diet with bacterial xylanase did not prevent diarrhoea of ETEC susceptible piglets, but favoured the persistence of Lactobacillus reuteri in the gut

Abstract

Exogenous enzymes can favour the release of shorter polymers of the dietary fibre, favouring the development of a beneficial digestive microflora. The addition of bacterial xylanase to a weaner pig diet was tested for its impact on the intestinal microbiota and digestive homeostasis. Thirty-two pigs genetically susceptible to enterotoxigenic Escherichia coli (ETEC), equally divided into two experimental groups, were used to increase the risk of diarrhoea and test the response of xylanase under conditions representing those severe situations which are frequently present on farms. Pigs, weaned at 25 ± 1 days, were fed a corn/barley standard diet without (Group CO) or with (Group XY) 100 g/t xylanase from BELFEED NV, Belgium. Blood samples (for measuring the reactive oxygen metabolites) and faeces were taken 14 and 28 days from the beginning of the trial. On day 28, the pigs were euthanised and jejunal samples were collected.The faecal bacteria16S rRNA gene was sequenced using a MiSeq Reagent Kit V3-V4 on a MiSeq-Illumina platform. The pigs had diffuse diarrhoea starting from day 4. On the morning of day 8 and for the two following days, all the pigs were treated with Enrofloxacin intramuscularly. The efficacy of the Enrofloxacin was confirmed using the ETEC F18 growth inhibition test. Four animals in each treatment group died or were suppressed to reduce pain. The diet did not change growth, the faecal score or the reactive oxygen metabolites in the blood. The XY treatment trended to increase villus length in the jejunum (p = 0.066). The operational taxonomic unit (OTU) distribution was fairly homogeneous, the microbial diversity indices were not changed by the treatment, and the per phylum abundances were homogenous among the diets and were dominated by Bacteroidetes and Firmicutes. The beneficial xylose-fermenting Lactobacillus reuteri persisted after weaning in the XY treatment group (P < 0.05). The Beta Diversity was clusterised for the time of sampling (P = 0.003). The supplementation with xylanase did not improve growth or protection against ETEC, but the effect on some beneficial bacteria species is merits additional study.